1. Field of the Invention
This invention relates to different embodiments of fluid control valves that are suitable for operating with human hand or foot forces, when the fluid pressure is extremely high, but are also suitable for operating with mechanical, electrical or fluidic power units. A "dump valve" or pressure relief valve has a relatively large dump port through which fluid pressure within a valve cavity can be quickly relieved or drastically reduced by manually operating a valve stem/poppet arrangement that opens and closes the dump port. A "closure valve" or fast-actuating on-off valve has a valve poppet capable of opening or closing a fluid outlet within the valve cavity. This invention provides a novel design and operating principle that translate into much improved dump valves and closure valves, particularly those suitable for high-pressure fluid flow control applications.
2. Description of Prior Art
New technology that has evolved during the recent fifteen years relates to generation and use of high-velocity waterjets, such technology often being referred to as high-pressure waterjetting technology. Conventional waterjets are commonly used to clean industrial and commercial equipment, with or without additives such as detergents or abrasives. In such applications, a hand held lance is used to aim the waterjet at the target. Such conventional waterjet lances are generally equipped with a hand or foot operated on-off valve or dump valve, depending upon several factors, such as the type of pump, fluid pressure, and the particular application. Currently, waterjetting is applied with conventional and manually operated valves at static water pressures in excess of 10,000 pounds per square inch (psi). At water pressures below 5,000 psi, a variety of conventional dump valves and closure valves can be operated by human hand or foot forces, for quick operation of a waterjet lance. Such conventional valves are reasonably safe and reliable. However, as the water pressure increases, operation of a fast-actuating fluid valve with human forces becomes difficult since the stresses from the fluid become very high and thus causes problems with fluidic sealing. Currently, conventional manually operated dump valves and closure valves have significant shortcomings, particularly those which operate at fluid pressures in excess of 10,000 psi. A high-pressure fluid control valve according to this invention eliminates such shortcomings.
In order to appreciate the novelty of this invention, it is necessary to describe prior art related to manually-operated dump valves and closure valves. Conventional waterjet lances equipped with a dump valve are commonly supplied by a positive displacement crank shaft pump that resembles a car or truck engine. Such positive displacement pump typically has three or five sets of cylinder and plunger arrangements, and is often driven with an electric motor or engine. Such pumps are capable of delivering water at high-pressures in excess of 10,000 psi. A conventional waterjet lance is generally tubular in form and has a hand or foot operated dump valve. Such dump valve has a fluid inlet port that is connected to a pump through a high-pressure hose or tube, a fluid outlet port that is connected to an outlet tube and ultimately connected to a nozzle assembly having a prescribed orifice for generating a high velocity waterjet to accomplish work, and a dump port that is connected to a short section of tubing.
U.S. Pat. No. 3,672,575 discloses a typical conventional dump valve used in waterjetting. FIG. 1 of my drawings shows a typical hand operated dump valve for waterjetting. According to FIG. 1, a conventional valve body 1 has a central cylindrical valve cavity 2 that is connected to a water inlet tube 3 and a water outlet tube 4, and has a valve seat 5 with a central dump port 6. The valve seat 5 can have a seal 7 and may be secured within a recess provided within the valve body 1 by a valve cover 8, anchor bolts 10 and a valve cover seal 9. The valve cover 8 has a fluid passage 11 which is in communication with the dump valve port 6 and a short dump tube 12. A cylindrical valve plunger 13 having a flat, coned or rounded end is mounted within the valve cavity 2 and is in contact with the valve seat 5. The valve plunger 13 is free to slide within the valve cavity 2, through a plunger seal assembly 14 which is positioned at an opposite end of the valve cavity 2. An opposite end of the valve plunger 13 is positioned outside of the valve cavity 2. The plunger seal assembly 14 has a cylindrical shoulder 15 and a bias spring 16. The valve plunger shoulder 15 and the associated bias spring 16 are generally positioned within a recess in the valve body 1. The valve plunger shoulder 15 is in contact with a cam end of an elongated valve trigger 17 which is pivotally mounted with respect to a valve handle 19. By pulling the valve trigger 17 against the valve handle 19, through the cam action, the valve plunger 13 is pushed or moved upward to seal off the dump port 6. Releasing the valve trigger 17 results in a downward movement of the valve plunger 13, due in part to the action of the bias spring 16. In waterjetting operations, pressurized water from a pump enters the valve through the inlet tube 3 and is discharged from the valve through both the outlet tube 4 and the dump tube 12. The dump port 6 is generally relatively large and thus the water is discharged from the valve at a relatively low velocity and corresponding low impact force.
To generate a relatively high impact waterjet according to the '575 patent, an operator must pull the valve trigger 17 against the handle 19 and thus cause the dump port 6 to be closed and sealed off by the valve plunger 13. As a result, the water is only discharged through the nozzle assembly at the end of the outlet tube 4. Since the nozzle assembly has a prescribed orifice of a significantly smaller size than the dump port 6, water inside the valve 20 builds up to a prescribed pressure level. When the operator releases the trigger 17, the waterjetting operation is stopped. The water would then be discharged from the valve 20 through both the nozzle and the dump tube 12, with the majority of the water being discharged through the dump tube 12, particularly without a relatively high impact force.
The dump valve according to the '575 patent is commonly used in waterjet lances. Other conventional devices have slight variations in the design of the components, particularly in the cam arrangement for moving the valve plunger. However, the basic operational principle remains the same throughout such conventional dump valves; a human hand or foot force is necessary to close the dump port and to maintain the dump port closed during the waterjetting operation. Other conventional dump valves may have a compression spring or springs to assist the manual operation, but the main force to maintain the dump port closed is still derived from the human hand or foot force. Closing the dump port in such conventional valves is accomplished with fluid pressure within the cavity at a relatively low level at the moment the dump port closes. However, such conventional dump valves present problems in maintaining the dump port closed during the waterjetting operations, particularly at the prescribed system operating pressure. For a conventional dump valve to properly function, the valve plunger and the valve seat must perfectly mate. The sealing circle between the valve plunger and the valve seat must be absolutely fluid tight and have a diameter only slightly smaller than the diameter of the valve plunger, so that the forces exerted on the valve plunger by the pressurized fluid within the cavity is relatively small for accommodating a normal hand force applied to the trigger.
The magnitude of fluid induced force on the valve plunger of a conventional dump valve can be quite significant and difficult to overcome by human hand forces, particularly if the valve plunger does not perfectly mate with the valve seat, which can be misaligned or worn out. For example, if the cross-sectional area of the valve plunger, as seen by the valve plunger seal assembly, is 0.001 in.sup.2 larger than the cross-sectional area of the seal circle on the valve seat, then a force of 20 lb.sub.f will be generated by 20,000 psi water within the valve, in a direction of pushing the valve plunger outward. To keep the dump port closed, the human hand must then provide sufficient force on the trigger to overcome the fluid force. Such situation can become less operable if the seal between the valve plunger and the valve seat is not perfect and pressurized water escapes into the contact surface between the valve plunger and the valve seat, due to the relatively large fluid induced force that may result on the valve plunger. Therefore, a common problem with conventional dump valves is leakage which thus causes human fatigue, since the constant hand force applied to the handle must be maintained to achieve the prescribed operating system pressure.
According to the '575 patent, if the diameter of the sealing circle on the valve seat is slightly larger than the diameter of the valve plunger, as seen by the plunger seal, then sealing the dump port will be assisted by pressurized fluid within the valve cavity, since the fluid induced forces are applied in a direction opposite of the pushing force of the plunger, as the plunger moves upward against the valve seat. In such case, the dump port will be difficult to open since the bias spring may not provide sufficient force to pull the valve plunger from its seat. If the bias forces of the spring are significantly increased, then the human hand force must fight the spring action at all times. Thus, it is obvious that there is a fine balance which must be maintained in order for the conventional dump valve to function properly. It is quite difficult to obtain such fine balance since the conventional dump valves in waterjetting operations are well known for their unreliability and difficult operation. Leakage of water through the dump port and required significant hand forces are often experienced. A high pressure fluid control valve according to this invention circumvents such shortcomings and provides more reliable and effective performance.
The "dead-end" valve or closure valve is another conventional manually operated flow control valve currently in use in the waterjetting industry. Such valve is basically a manually operated fast-actuating on-off valve. FIG. 2 of the drawings of this disclosure shows a conventional closure valve 30 having valve body 31 with central cylindrical valve cavity 32 in communication with inlet tube 33 and outlet tube 34. Valve seat 35 is mounted within valve cavity 32 and has central outlet port 36. Lever trigger 37 and its pivot 38 are used to engage pivoting cam assembly 50, which engages sliding piston 45. Sliding piston 45 is mounted within cylindrical cavity 51, axially in line with valve cavity 32. Handle 39 is attached to valve body 31 with anchor bolts 40. Cylindrical valve stem 43 is mounted within valve cavity 32 and has a coned tip or an attached valve poppet for opening and closing outlet port 36. The outer end of valve stem 43 extends outside of valve cavity 32, through stem seal assembly 44, and into cylindrical cavity 51 to contact stem piston 45. Valve stem 43 and stem piston 45 can be either an integral piece or two separate components. The opposite end of stem piston 45 abuts stem spring 46 which provides a force necessary for normally closing outlet port 36.
When the valve assembly of FIG. 2 is not in use, stem spring 46 is installed into valve body 31 under compression and thus exerts constant force against stem piston 46 from right to left, as shown in FIG. 2, and thus forces valve stem 43 into a normally closed and seated position against valve seat 35, thereby closing outlet port 36. Such force must be strong enough so that outlet port 36 remains closed when pressurized fluid is introduced into valve assembly 30. To open valve assembly 30, a user applies hand forces against trigger 37 and thereby pulls trigger 37 toward handle 39. Through cam assembly 50, the pulling force upon trigger 37, toward handle 39, produces a force pushing stem piston 45 from left to right, as shown in FIG. 2. Stem spring 46 is thus compressed and valve stem 43 is pushed by fluid forces from left to right, as shown in FIG. 2, thus opening outlet port 36. FIG. 3 illustrates an open position of outlet port 36, according to the conventional closure valve as shown in FIG. 2.
Conventional closure valves vary in design, particularly in the mechanical linkage used to produce sliding motion of the valve stem. However, most conventional closure valves share the same basic operating principle which requires hand forces to overcome a spring force in order to initially open and maintain open the fluid outlet of the valve assembly. Furthermore, releasing such hand force with conventional closure valves results in restoring the spring force exerted against the valve stem and thereby closing the fluid outlet of the valve assembly. Such basic operating principles of the conventional closure valves indicates that several design aspects are vital to proper functioning of such conventional closure valves. For example, the stem spring must provide a force significantly greater than the fluidic force exerted on the valve stem when the outlet port is open. The hand force applied to the valve stem through the trigger lever and cam assembly must be greater than the total force involved in seating the valve stem against the valve seat when closing the fluid outlet of the valve assembly. Also, there must be a net force in favor of opening the fluid outlet from the pressurized fluid, if the valve stem and the valve piston are two separate components. In other words, the outlet port must not have a diameter greater than the diameter of the valve stem, as seen by the seal assembly. Furthermore, if the valve stem and the stem piston are an integral component or are tightly engaged, then the hand force applied to the trigger level must include the force necessary for unseating the valve stem from the valve seat.
It is thus apparent that in order for conventional closure valves to function at relatively high fluid pressures, there must exist a fine force balance within the valve assembly. For example, if the diameter of valve stem 43, as shown in FIGS. 2 and 3, is 0.125 inches, then the total cross-sectional area is 0.0123 in.sup.2. If the valve is operated at a fluid pressure of 30,000 psi, a force of 368 lb.sub.f, which is the product of the fluid pressure and the cross-sectional area of the valve stem, will be exerted against the valve stem when the outlet port is opened and the valve assembly is operating. Such fluid force of 368 lb.sub.f is combined with a hand force to keep the stem spring further compressed and to keep the outlet port open. When the hand force is released, valve spring 46 must provide a force greater than 368 lb.sub.f in an opposite direction of the fluid induced force on the valve stem, in order to close the outlet port. These forces can only be achieved by using large die springs that are impractical for use in hand held devices. Thus, conventional closure valves are designed to reduce the diameter of the valve stem to a relatively small dimension, such as 0.063 inches, which corresponds to a cross-sectional area of 0.0031 in.sup.2, or 92 lb.sub.f at a static fluid pressure of 30,000 psi. Such 92 lb.sub.f can be overcome with 1-inch diameter die springs. Unfortunately, valve stems having a diameter of 0.063 inches are not strong enough, even if constructed of exotic metals, particularly if they are exposed to bending stresses. Using such small diameter valve stems also limits the size of the fluid outlet ports to a relatively small dimension, and thus increases the fluid pressure drop when fluid is flowing through the valve during waterjetting operations. Such valve stems reduce the overall effectiveness of the conventional valve. Thus, conventional closure valves used in waterjetting operations have serious shortcomings, particularly with respect to pressure capabilities. At relatively high fluid pressures, conventional valve stems are likely to break and thus create unsafe operating conditions. This invention overcomes such shortcomings and unsafe operating conditions and provides a superior closure valve for relatively high-pressure fluid control operations.